1 Department of Diagnostic Imaging, Hospital for Sick Children, Toronto, Ontario, Canada M5G 1X8.
Program in Neurosciences & Mental Health, Hospital for Sick Children, Toronto, Ontario, Canada M5G 1X8.
Cereb Cortex. 2017 Aug 1;27(8):4094-4105. doi: 10.1093/cercor/bhw221.
Identifying trajectories of early white matter development is important for understanding atypical brain development and impaired functional outcomes in children born very preterm (<32 weeks gestational age [GA]). In this study, 161 diffusion images were acquired in children born very preterm (median GA: 29 weeks) shortly following birth (75), term-equivalent (39), 2 years (18), and 4 years of age (29). Diffusion tensors were computed to obtain measures of fractional anisotropy (FA), mean diffusivity (MD), axial diffusivity (AD), and radial diffusivity (RD), which were aligned and averaged. A paediatric atlas was applied to obtain diffusion metrics within 12 white matter tracts. Developmental trajectories across time points demonstrated age-related changes which plateaued between term-equivalent and 2 years of age in the majority of posterior tracts and between 2 and 4 years of age in anterior tracts. Between preterm and term-equivalent scans, FA rates of change were slower in anterior than posterior tracts. Partial least squares analyses revealed associations between slower MD and RD rates of change within the external and internal capsule with lower intelligence quotients and language scores at 4 years of age. These results uniquely demonstrate early white matter development and its linkage to cognitive functions.
识别早期大脑白质发育轨迹对于理解极早产儿（<32 孕周）大脑发育异常和功能受损结局至关重要。本研究纳入 161 例极早产儿（中位孕周 29 周），分别在出生后不久（75 例）、胎龄矫正至足月（39 例）、2 岁（18 例）和 4 岁（29 例）时进行弥散张量成像检查。计算各向异性分数（FA）、平均弥散度（MD）、轴向弥散度（AD）和径向弥散度（RD）等弥散张量参数，并进行对齐和平均处理。应用儿科图谱获取 12 条白质纤维束的弥散张量参数。结果显示，各时间点的发育轨迹均随年龄变化而变化，多数后纤维束在胎龄矫正至足月和 2 岁时趋于稳定，前纤维束在 2 至 4 岁时趋于稳定。与胎龄矫正至足月扫描相比，前纤维束的 FA 变化率在早产儿中较慢。偏最小二乘法分析显示，外部和内部囊壳的 MD 和 RD 变化率较慢与 4 岁时的智商和语言评分较低有关。这些结果首次表明早期大脑白质发育与认知功能相关。
